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摘要
Deterioration of concrete in marine environment was usually caused by chloride and sulfate attacks, and incorporating supplementary cementitious materials (SCMs) was an effective way to improve the resistance of concrete for ions attack. Although the utilization of fine cementitious materials with high hydraulic activity was beneficial to the development of mechanical properties and ions attack resistance, it would result in the poor flowability, significant internal stress, and high cracking risk of cement paste. In present study, on the basic of Dinger-Andersen particle distribution model, fine blast furnace slag and coarse fly ash were introduced into commercial Portland cement, the metakaolin was also adopted as functional component, and then the densified quadruple blended cement containing 60% SCMs was prepared. The prepared blended cement presented comparable strength with Portland cement at the early age and much higher resistance for chloride or sulfate attacks at 28 d. The RCM chloride diffusion coefficient of quadruple blended cement decreased 81% compared with Portland cement, and its index of residual strength after 30 drying-wetting cycles in sulfate solution was as high as 77%. The higher packing density and continuous hydration of quadruple blended cement paste led to significant pore size refinement and formation of products with higher chloride binding capacity, which helped block the ingress of aggressive ions from external. Moreover, more Ca(OH)2 was consumed due to efficient hydration of SCMs in quadruple blended cement, and the secondary ettringite formation was limited. According to the microstructural design of cement paste, the hydraulic activity of cementitious materials can be efficiently utilized, and the structural compactness of blended cement and its resistance to ions attacks can be improved subsequently. ? 2023 Cailiao Daobaoshe/ Materials Review.
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